Core-shell graft copolymers with improved surface properties

ABSTRACT

Disclosed herein is a core-shell graft copolymer produced by coagulation of an aqueous latex comprising a quantity of particles of the copolymer and a quantity of a fatty acid surfactant, wherein the coagulation involves the addition of a quantity of a multivalent metal salt, preferably a bivalent or trivalent metal salt. Such copolymer provides in an improvement of the surface properties of moulded articles produced from such copolymers, as demonstrated by a reduction of the content of gels in the surface layer.

The present application claims priority to EP 17201997.8 filed on Nov.16, 2017, which is incorporated herein in its entirety.

The present invention relates to core-shell graft copolymers havingimproved surface properties. In particular, the invention relates tocore-shell graft copolymers having improved surface properties whencoated with a metallic coating. The invention further relates to aprocess for producing such core-shell graft copolymers. The inventionalso related to articles comprising a surface area of such core-shellgraft copolymer, in particular to articles comprising a surface area ofsuch core-shell graft copolymer where the surface is coated with ametallic coating.

The external surface structure is considered an important characteristicfor many different articles. Where articles or parts of articles aremanufactured from polymeric materials, is tends to be particularlydesired that the surfaces of such articles that are made up of thosepolymeric materials demonstrate a very low quantity of surface defects.This is certainly the case in the situation where such surface iscovered with a metallic coating. In many articles, including for examplehousehold appliances and vehicle interior parts, the use of parts madefrom polymeric materials to which a metallic coating is applied iswidespread. Such parts demonstrate the appearance of a metallic part,but still are for the main part produced from polymeric materials, andthus provide all the advantages of such polymeric materials, includingfor example weight reduction, the ability to produce wide varieties ofcomplex shapes, and reduced cost of production.

One group of polymeric materials that are commonly used in articles witha metallic coating are core-shell graft copolymers. A particular exampleof suitable core-shell graft copolymers are copolymers comprisingelastomeric cores structures to which a thermoplastic polymer is graftcopolymerised. Such copolymers have good impact strength properties andgood elastic modulus properties, whilst still having hardness propertiessuch to allow the use in articles where a particular surface scratchresistance is required. As quality requirements continue to increase,there continues to be a need to have access to polymeric materials that,when shaped into a moulded part and provided with a metallic coating,demonstrate a uniform surface with as little as surface defects aspossible.

WO 2012/080407 is directed to a thermoplastic polymer especiallysuitable for metal plating resulting in metal plated finished articleshaving improved resistance against repeated impacts, while maintainingsufficient thermal stability, surface quality, superior adhesion betweenthe substrate and the metal layer irrespective of the complexity of thedesign of the molded article and the kind of metal plating technique(e.g. conventional, electroless, physical vapour deposition, directmetal plating). The thermoplastic moulding composition is produced froma graft copolymer (A) a thermoplastic polymer that has a moisturecontent of 0 to 27% by weight after work-up (B). Preferably, thecomposition additionally includes a thermoplastic polymer (C) that isnot, or only to a limited amount, miscible with the thermoplasticpolymer (B).

JP 2006291051 is directed to a thermoplastic resin composition. Thethermoplastic resin composition comprises (B) a rubbery graft copolymerobtained by graft copolymerization of a vinyl monomer to a rubber in thepresence of (A) a fatty acid-based surfactant wherein the counterion issodium ion and coagulated with a calcium salt and (C) a polyacetalresin.

WO 2006/127223 is directed to a molding composition comprising anacrylic-styrene-acrylonitrile (ASA) resin comprising a discontinuouselastomeric phase dispersed in a rigid thermoplastic phase, wherein atleast a portion of the rigid thermoplastic phase is grafted to theelastomeric phase; and wherein the thermoplastic phase comprisesstructural units derived from at least one vinyl aromatic monomer, atleast one monoethyleni catty unsaturated nitrile monomers, andoptionally at least one (C1-C12)alkyl- and aryl-(meth)acrylate monomer;and wherein the elastomeric phase is derived from a rubber substratecomprising structural units derived from at least one(C1-C12)alkyl(meth)acrylate monomer and at least one crosslinking agentcomprising a polyethylenically unsaturated monomer; and wherein therubber substrate comprises less than 5.6 micromoles of unreactedcrosslinking agent per gram of rubber substrate based on the dry weightof the rubber substrate before grafting.

EP 2465883 is directed to an impact modifier in form of a core-shellcopolymer impact modifier particle comprising a polymeric core and atleast two polymeric layers, each layer with a different polymercomposition, wherein at least one polymeric layer comprises a polymerthat is a gradient polymer.

Further, improved requirements with regard to surface quality ofarticles made from polymeric materials continue to be requested also forapplications besides articles with a metallic coating. The provision ofmaterials allowing for production of articles with further reducedsurface defects persists to be desired.

Disclosed herein is a core-shell graft copolymer produced by coagulationof an aqueous latex comprising a quantity of particles of the copolymerand a quantity of a fatty acid surfactant, wherein the coagulationinvolves the addition of a quantity of a multivalent metal salt,preferably a bivalent or trivalent metal salt, or a lithium salt.

Such copolymer provides an improvement of the surface properties ofmoulded articles produced from such copolymers, as demonstrated by areduction of the content of gels in the surface layer.

The core-shell graft copolymer may for example comprise elastomeric coreparticles and thermoplastic polymeric chains. In the core-shellcopolymer, it is preferred that at least a fraction of the thermoplasticpolymeric chains is covalently bound to the elastomeric core particlesto form a graft copolymer. The core-shell graft copolymer may forexample comprise a quantity of elastomeric core particles onto which afraction of thermoplastic polymeric chains is covalently bound, and aquantity of thermoplastic polymeric chains that are not covalently boundto elastomeric core particles.

The core-shell graft copolymer may for example comprise greater than orequal to (≥) 10.0 weight percent (wt %) of elastomeric core particleswith regard to the total weight of the core-shell graft copolymer,preferably ≥20.0 wt %, more preferably ≥30.0 wt %, even more preferably≥40.0 wt %.

The core-shell graft copolymer may for example comprise less than orequal to (≤) 80.0 wt % of elastomeric core particles, preferably ≤70.0wt %, more preferably ≤60.0 wt %, even more preferably ≤50.0 wt %.

The core-shell graft copolymer may for example comprise ≥10.0 wt % and≤80.0 wt % of elastomeric core particles, preferably ≥20.0 wt % and≤70.0 wt %, more preferably ≥30.0 wt % and ≤60.0 wt %, even morepreferably ≥40.0 wt % and ≤60.0 wt %.

The elastomeric core particles may for example have an average particlesize of ≥100 nanometers (nm), preferably ≥150 nm, more preferably ≥200nm, even more preferably ≥250 nm. The elastomeric core particles may forexample have an average particle size of ≤1,000 nm, preferably ≤500 nm,more preferably ≤400 nm. The elastomeric core particles may for examplehave an average particle size of ≥100 nm and ≤1000 nm, preferably ≥150nm and ≤500 nm, more preferably ≥200 nm and ≤400 nm.

As disclosed herein, the average particle size may be understood to bethe D₅₀ particle size as determined in accordance with ISO 9276-2(2014).

The elastomeric core particles may for example be polymers producedusing compounds comprising at least 2 unsaturated carbon-carbon bonds asmonomers, or polymers produced using compounds comprising one or moreacrylate moieties as monomers, or combinations of such polymers.

Examples of compounds comprising at least 2 unsaturated carbon-carbonbonds include for example butadiene, isoprene, chloroprene,2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 1,2-propadiene,1,4-pentadiene, 1,2-pentadiene, 1,5-hexadiene, or combinations thereof.It is preferred that the compound comprising at least 2 unsaturatedcarbon-carbon bonds is butadiene.

Examples of polymers produced using compounds comprising at least 2unsaturated carbon-carbon bonds as monomers include for examplepolybutadiene, polyisoprene, poly(styrene-butadiene),poly(acrylonitrile-styrene), poly(styrene-isoprene),poly(isoprene-butadiene), or combinations thereof. It is preferred thatthe polymer obtained from compounds comprising at least 2 unsaturatedcarbon-carbon bonds is polybutadiene.

Examples of compounds comprising one or more acrylate moieties includefor example methyl acrylate, ethyl acrylate, butyl acrylate,2-ethylhexyl acrylate, cyclohexyl acrylate, benzyl acrylate, isopropylacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate,isopropyl methacrylate, cyclohexyl methacrylate, or combinationsthereof. It is preferred that the compound comprising one or moreacrylate moieties is butyl acrylate.

Examples of polymers produced using compounds comprising one or moreacrylate moieties as monomers include for example ethylene acrylicelastomers and poly(n-butyl acrylate). The polymer produced usingcompounds comprising one or more acrylate moieties as monomers can bepoly(n-butyl acrylate).

It is preferred that the elastomeric core particles are selected frompolybutadiene particles, polyacrylate particles such aspolybutylacrylate particles, or poly(styrene-butadiene) particles.

The core-shell graft copolymer may for example be produced bypolymerisation of the elastomeric core particles with a quantity of oneor more monomer(s). The monomer(s) may for example be one or more ofstyrene, alpha-methyl styrene, vinyl toluene, vinyl chlorobenzene, vinylbromobenzene, acrylonitrile, methacrylonitrile, methyl methacrylate,methyl acrylate, ethyl methacrylate, ethyl acrylate, butyl acrylate,maleic anhydride, or N-phenylmaleimide.

The core-shell graft copolymer may for example comprise ≥5.0 wt % ofpolymeric chains graft copolymerised onto the elastomeric coreparticles, with regard to the total weight of the core-shell graftcopolymer, preferably ≥10.0 wt %, more preferably ≥15.0 wt %.

The core-shell graft copolymer may for example comprise ≤50.0 wt % ofpolymeric chains graft copolymerised onto the elastomeric coreparticles, with regard to the total weight of the core-shell graftcopolymer, preferably ≤40.0 wt %, more preferably ≤30.0 wt %, even morepreferably ≤20.0 wt %.

The core-shell graft copolymer may for example comprise ≥5.0 wt % and≤50.0 wt % of polymeric chains graft copolymerised onto the elastomericcore particles, with regard to the total weight of the core-shell graftcopolymer, preferably ≥5.0 wt % and ≤30 wt %, more preferably ≥10.0 wt %and ≤20.0 wt %.

The core-shell graft copolymer may for example comprise ≥20.0 wt % ofpolymeric chains that are not covalently bound the elastomeric coreparticles, with regard to the total weight of the core-shell graftcopolymer, preferably ≥30.0 wt %, more preferably ≥40.0 wt %. Thecore-shell graft copolymer may for example comprise ≤75.0 wt % ofpolymeric chains that are not covalently bound to the elastomeric coreparticles, with regard to the total weight of the core-shell graftcopolymer, preferably ≤65.0 wt %, more preferably ≤55.0 wt %. Thecore-shell graft copolymer may for example comprise ≥20.0 wt % and ≤75.0wt % of polymeric chains that are not covalently bound to theelastomeric core particles, with regard to the total weight of thecore-shell graft copolymer, preferably ≥30.0 wt % and ≤65.0 wt %, morepreferably ≥40.0 wt % and ≤55.0 wt %.

The polymeric chains that are graft copolymerised onto the elastomericcore particles may for example be polymeric chains derived from one ormore monomers selected from vinyl aromatic compounds, vinyl cyanidecompounds, or compounds comprising one or more acrylate moieties.

The polymeric chains that are not covalently bound to the elastomericcore particles may for example be polymeric chains derived from one ormore monomers selected from vinyl aromatic compounds, vinyl cyanidecompounds, or compounds comprising one or more acrylate moieties.

The polymeric chains that are graft copolymerised onto the elastomericcore particles and the polymeric chains that are not covalently bound tothe elastomeric core particles may for example be derived from the samemonomer(s). Alternatively, the polymeric chains that are graftcopolymerised onto the elastomeric core particles and the polymericchains that are not covalently bound to the elastomeric core particlesmay for example be derived from different monomer(s). Preferably, thepolymeric chains that are graft copolymerised onto the elastomeric coreparticles and the polymeric chains that are not covalently bound to theelastomeric core particles are derived from the same monomer(s).

Examples of vinyl aromatic compounds include for example styrene,α-methyl styrene, halostyrenes such as dibromostyrene, vinyltoluene,vinylxylene, butylstyrene, p-hydroxystyrene, methoxystyrene, orcombinations thereof. Particularly the vinyl aromatic compounds caninclude, for example styrene and α-methyl styrene. It is preferred thatthe vinyl aromatic compound is styrene.

Examples of vinyl cyanide compounds include for example acrylonitrile,methacrylonitrile, ethacrylonitrile, α-chloroacrylonitrile,α-bromoacrylonitrile, or combinations thereof. It is preferred that thevinyl cyanide compound is acrylonitrile.

Examples of compounds comprising one or more acrylate moieties includefor example methyl acrylate, ethyl acrylate, butyl acrylate,2-ethylhexyl acrylate, cyclohexyl acrylate, benzyl acrylate, isopropylacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate,isopropyl methacrylate, cyclohexyl methacrylate, or combinationsthereof. Particularly, the compound comprising one or more acrylatemoieties may be selected from methyl acrylate or methyl methacrylate.

Preferably, the polymeric chains that are graft copolymerised onto theelastomeric core particles and the polymeric chains that are notcovalently bound to the elastomeric core particles are derived from oneor more monomer(s) selected from acrylonitrile, styrene, α-methylstyrene, or methyl methacrylate. It is particularly preferred that thepolymeric chains that are graft copolymerised onto the elastomeric coreparticles and the polymeric chains that are not covalently bound to theelastomeric core particles are derived from acrylonitrile and styrene.The polymeric chains may for example be produced using a reactionmixture comprising styrene and acrylonitrile wherein the molar ratio ofstyrene to acrylonitrile is in the range of 1.5-4.0.

For example, the core-shell graft copolymer may be produced using areaction mixture comprising elastomeric core particles and one or moremonomer(s) selected from acrylonitrile, styrene, α-methyl styrene, ormethyl methacrylate. The molar ratio of the elastomeric core particlesto the total of the monomer(s) may for example be in the range of0.1-3.0, preferably in the range of 0.2-2.0.

The core-shell graft copolymer can be produced using a reaction mixturecomprising elastomeric core particles and a mixture of monomerscomprising acrylonitrile and styrene. It is particularly preferred thatthe core-shell graft copolymer is produced using a reaction mixturecomprising elastomeric core particles and a mixture of monomersconsisting of acrylonitrile and styrene. Even further, it is preferredthat the core-shell graft copolymer is produced using a reaction mixturecomprising elastomeric core particles wherein the elastomeric coreparticles are at least one of polybutadiene particles,poly(n-butyl)acrylate particles, or poly(styrene-butadiene) particles,and a mixture of monomers comprising acrylonitrile and styrene. Evenfurther preferably, the core-shell graft copolymer is produced using areaction mixture comprising elastomeric core particles wherein theelastomeric core particles are polybutadiene particles, and a mixture ofmonomers comprising acrylonitrile and styrene.

The elastomeric core particles can be with at least two distinguishablepeaks on particle size distribution, which is determined by a BeckmanCoulter multi-wavelength laser diffraction particle size analyser typeLS 13320 in accordance with ISO 13320. The first peak is at <200nanometers (nm). The second peak is at 200-500 nm. A possible third peakcan be at >800 nm with >0.1% volume percentage. Such particle sizedistribution elastomeric core particles can be produced by processingthe monodistributed particles latex through high pressure mechanicalhomogenizer. Hence, the elastomeric core particles can be trimodal.

Optionally, the core-shell graft copolymer can be produced using areaction mixture comprising elastomeric core particles wherein theelastomeric core particles are polybutadiene particles, and a mixture ofmonomers comprising acrylonitrile and styrene, wherein the molar ratioof styrene to acrylonitrile is in the range of 1.5-4.0, preferably2.0-3.0, and the molar ratio of polybutadiene to the sum of styrene andacrylonitrile is in the range of 0.1-3.0, preferably 0.2-2.0.

For example, the core-shell graft copolymer may be anacrylonitrile-butadiene-styrene (ABS) graft copolymer, a methylmethacrylate-butadiene-styrene graft copolymer, or anacrylonitrile-styrene-acrylate rubber graft copolymer. In a preferredembodiment, the core-shell graft copolymer is anacrylonitrile-butadiene-styrene graft copolymer.

The core-shell graft copolymer may for example have an average particlesize D₅₀ of ≥0.02 micrometer (μm), preferably ≥0.05 μm, more preferably≥0.10 μm. The core-shell graft copolymer may for example have an averageparticle size D₅₀ of ≤3.00 μm, preferably ≤2.00 μm, more preferably≤1.00 μm. The core-shell graft copolymer may for example have an averageparticle size D₅₀ of ≥0.02 μm and ≤3.00 μm, preferably ≥0.05 μm and≤2.00 μm, more preferably ≥0.10 μm and ≤1.00 μm.

The aqueous latex comprises a quantity of particles of the core-shellgraft copolymer. The aqueous latex may for example comprise ≥10.0 wt %of particles of the core-shell graft copolymer with regard to the totalweight of the aqueous latex, preferably ≥20.0 wt %, more preferably≥30.0 wt %. The aqueous latex may for example comprise ≤70.0 wt % of thecore-shell graft copolymer with regard to the total weight of theaqueous latex, preferably ≤60.0 wt %, more preferably ≤50.0 wt %, stillmore preferably less than (<) 40.0 wt %, or ≤35.0 wt %. The aqueouslatex may for example comprise ≥10 wt % and ≤70.0 wt % of the core-shellgraft copolymer with regard to the total weight of the aqueous latex,preferably ≥20.0 wt % and ≤60.0 wt %, more preferably ≥30.0 wt % and≤50.0 wt %. Preferably the aqueous latex can comprise ≥10.0 wt % and <40wt % particles of the core-shell graft copolymer with regard to thetotal weight of the aqueous latex, more preferably ≥20.0 wt % and ≤35.0wt %, or ≥25.0 wt % and ≤35.0 wt %. For example, if the core-shellcopolymer contains more than 40 wt % butadiene rubber, it may causerubber agglomeration in the compounding step due to less surfacecoverage of SAN to the rubber core. This can result more defects in thefinal article surface after processing to make the metallic coating.

The aqueous latex comprising the core-shell graft copolymer can furthercomprise a quantity of a surfactant. For example, the aqueous latex maycomprise 0.1-5.0 wt % of surfactant, with regard to the total weight ofthe aqueous latex, preferably 0.5-3.0 wt %.

The surfactant may for example be a fatty acid or a salt thereof, or amixture of fatty acids or salts thereof. The fatty acid salt may be apotassium salt, a magnesium salt, a sodium salt, or a calcium salt.Preferably, the fatty acid salt is a potassium salt.

The fatty acid may be a single compound or a mixture of fatty acids. Thefatty acid may be a saturated fatty acid, a monounsaturated fatty acid,a polyunsaturated fatty acid, or mixtures thereof. The fatty acid mayfor example be selected from dodecanoic acid, tetradecanoic acid,hexadecanoic acid, octadecanoic acid, eicosanoic acid, docosanoic acid,dodecenoic acid, tetradecenoic acid, hexadecenoic acid, octadecenoicacid, eicosenoic acid, docosenoic acid, dodecadienoic acid,tetradecadienoic acid, hexadecadienoic acid, octadecadienoic acid,eicosadienoic acid, docosadienoic acid, and mixtures of such compounds.

For example, the surfactant may be tallow fatty acid or tallow fattyacid potassium salt. Preferably, the surfactant is tallow fatty acidpotassium salt.

The surfactant may for example be selected from fatty acids comprising≥14 and ≤20 carbon atoms, preferably comprising ≤5 unsaturations, ormixtures thereof.

The core-shell graft copolymer disclosed herein can be produced bycoagulation of an aqueous latex comprising a quantity of particles ofthe copolymer and a quantity of a surfactant, wherein the coagulationinvolves the addition of a quantity of a multivalent metal salt,preferably a bivalent or trivalent metal salt. For example, themultivalent metal salt may be a bivalent metal salt.

The multivalent metal salt may for example be a salt of beryllium,magnesium, calcium, strontium, barium, radium, aluminium or zinc.Preferably, the multivalent metal salt is a salt of magnesium,aluminium, zinc, or calcium. More preferably, the multivalent metal saltis a calcium salt.

The multivalent metal salt may for example be a halogenide (preferably achloride), a sulphate, a biphosphate, a hydrogen phosphate, abisulphate, a bicarbonate, a chlorate, or a nitrate. Preferably, themultivalent metal salt is a metal halogenide, for example a metalchloride.

The multivalent metal salt may for example be a salt of an alkalineearth metal.

For example, the multivalent metal salt may be selected from magnesiumsulphate, magnesium chloride, magnesium nitrate, calcium chloride,calcium nitrate, aluminium chloride, aluminium nitrate, zinc chloride,zinc sulphate, and zinc nitrate. Preferably, the multivalent metal saltis calcium chloride.

A quantity of for example 0.5-2.5 wt %, preferably 1.0-2.0 wt %, of themultivalent metal salt may be added for coagulation to the aqueouslatex, with regard to the total weight of the aqueous latex. Forexample, a quantity of 0.5-2.5 wt %, preferably 1.0-2.0 wt %, of themultivalent metal salt may be added for coagulation to the aqueouslatex, with regard to the total weight of the aqueous latex, wherein themultivalent metal salt is selected from magnesium sulphate, magnesiumchloride, magnesium nitrate, calcium chloride, calcium nitrate,aluminium chloride, aluminium nitrate, zinc chloride, zinc sulphate andzinc nitrate. Preferably, a quantity of 0.5-2.5 wt %, preferably 1.0-2.0wt %, of the multivalent metal salt is added for coagulation to theaqueous latex, with regard to the total weight of the aqueous latex,wherein the multivalent metal salt is calcium chloride.

Also disclosed herein is a process for the production of a core-shellgraft copolymer comprising coagulation of an aqueous latex comprising aquantity of particles of the copolymer and a quantity of a fatty acidsurfactant, wherein the coagulation involves the addition of 0.5-2.5 wt% of a multivalent metal salt with regard to the weight of thecore-shell copolymer particles present in the latex.

In this process, the metal may for example be selected from beryllium,magnesium, calcium, strontium, barium, radium, aluminium and zinc, andis preferably magnesium, aluminium, zinc and calcium; and/or the saltmay be a halogenide, preferably a chloride, a sulphate, a biphosphate, ahydrogen phosphate, a bisulphate, a bisulphite, a bicarbonate, achlorate, or a nitrate.

In this process, the core-shell graft copolymer may for example be oneselected from an acrylonitrile-butadiene-styrene graft copolymer, amethyl methacrylate-butadiene-styrene graft copolymer, anacrylonitrile-styrene-acrylate rubber graft copolymer, and anacrylonitrile-styrene-silicone rubber graft copolymer, and themultivalent metal salt may be one selected from magnesium sulphate,magnesium chloride, magnesium nitrate, calcium chloride, calciumnitrate, aluminium chloride, aluminium nitrate, zinc chloride, zincsulphate, and zinc nitrate.

Further disclosed herein are articles comprising a surface areacomprising a core-shell graft copolymer. In particular, the inventionrelates to articles wherein said surface area is coated with a metalliccoating. For example, such metallic coating may be applied viaelectroplating. In certain preferred embodiments the metallic coating isselected from copper, nickel, gold, silver, platinum, or alloys thereof.

A core-shell graft copolymer can be produced by coagulation of anaqueous latex comprising a quantity of particles of the copolymer and aquantity of a surfactant, wherein the coagulation involves the additionof a quantity of a multivalent metal salt, preferably a bivalent ortrivalent metal salt, wherein the core-shell graft copolymer comprises aquantity of elastomeric core particles onto which a fraction ofthermoplastic polymer chains is covalently bound, and a quantity ofthermoplastic polymer chains that are not covalently bound to theelastomeric core particles, wherein the elastomeric core particles arepolybutadiene particles, and the thermoplastic polymer chains arepoly(styrene-acrylonitrile) chains.

A core-shell graft copolymer can be produced by coagulation of anaqueous latex comprising a quantity of particles of the copolymer and aquantity of a surfactant, wherein the coagulation involves the additionof a quantity of a multivalent metal salt, wherein the multivalent metalsalt is calcium chloride, wherein the core-shell graft copolymercomprises a quantity of elastomeric core particles onto which a fractionof thermoplastic polymer chains is covalently bound, and a quantity ofthermoplastic polymer chains that are not covalently bound to theelastomeric core particles, wherein the elastomeric core particles arepolybutadiene particles, and the thermoplastic polymer chains arepoly(styrene-acrylonitrile) chains.

A core-shell graft copolymer can be produced by coagulation of anaqueous latex comprising a quantity of particles of the copolymer and aquantity of a surfactant, the surfactant being a fatty acid or saltthereof or a mixture of fatty acids or salts thereof, wherein thecoagulation involves the addition of a quantity of a multivalent metalsalt, wherein the multivalent metal salt is calcium chloride, whereinthe core-shell graft copolymer comprises a quantity of elastomeric coreparticles onto which a fraction of thermoplastic polymer chains iscovalently bound, and a quantity of thermoplastic polymer chains thatare not covalently bound to the elastomeric core particles, wherein theelastomeric core particles are polybutadiene particles, and thethermoplastic polymer chains are poly(styrene-acrylonitrile) chains.

A core-shell graft copolymer can be produced by coagulation of anaqueous latex comprising a quantity of particles of the copolymer and aquantity of a surfactant, the surfactant being a fatty acid or saltthereof or a mixture of fatty acids or salts thereof, wherein thecoagulation involves the addition of a quantity of a multivalent metalsalt, wherein the multivalent metal salt is calcium chloride, whereinthe core-shell graft copolymer comprises a quantity of elastomeric coreparticles onto which a fraction of thermoplastic polymer chains iscovalently bound, and a quantity of thermoplastic polymer chains thatare not covalently bound to the elastomeric core particles, wherein theelastomeric core particles are polybutadiene particles, and thethermoplastic polymer chains are poly(styrene-acrylonitrile) chains, andwherein multivalent metal salt is added to the aqueous latex in aquantity of 0.5-2.5 wt % with regard to the total weight of thecore-shell graft copolymer particles present in the latex.

A core-shell graft copolymer can be produced by coagulation of anaqueous latex comprising a quantity of particles of the copolymer and aquantity of a surfactant, the surfactant being a fatty acid or saltthereof or a mixture of fatty acids or salts thereof, wherein thecoagulation involves the addition of a quantity of a multivalent metalsalt, wherein the multivalent metal salt is calcium chloride, whereinthe core-shell graft copolymer comprises a quantity of elastomeric coreparticles onto which a fraction of thermoplastic polymer chains iscovalently bound, and a quantity of thermoplastic polymer chains thatare not covalently bound to the elastomeric core particles, wherein theelastomeric core particles are polybutadiene particles, and thethermoplastic polymer chains are poly(styrene-acrylonitrile) chains,wherein multivalent metal salt is added to the aqueous latex in aquantity of 0.5-2.5 wt % with regard to the total weight of thecore-shell graft copolymer particles present in the latex, wherein thecopolymer particles in the aqueous latex have an average particlediameter D₅₀ of ≥0.02 μm and ≤3.00 μm.

A core-shell graft copolymer can be produced by coagulation of anaqueous latex comprising a quantity of particles of the copolymer and aquantity of a surfactant, the surfactant being a fatty acid or saltthereof or a mixture of fatty acids or salts thereof, wherein thecoagulation involves the addition of a quantity of a multivalent metalsalt, wherein the multivalent metal salt is calcium chloride, whereinthe core-shell graft copolymer comprises a quantity of elastomeric coreparticles onto which a fraction of thermoplastic polymer chains iscovalently bound, and a quantity of thermoplastic polymer chains thatare not covalently bound to the elastomeric core particles, wherein theelastomeric core particles are polybutadiene particles, and thethermoplastic polymer chains are poly(styrene-acrylonitrile) chains,wherein multivalent metal salt is added to the aqueous latex in aquantity of 0.5-2.5 wt % with regard to the total weight of thecore-shell graft copolymer particles present in the latex, wherein thecopolymer particles in the aqueous latex have an average particlediameter D₅₀ of ≥0.02 μm and ≤3.00 μm,wherein the fatty acid comprises≥14 and ≤20 carbon atoms, and comprises ≤5 unsaturations.

The invention will now be illustrated by the following non-limitingexamples.

Coagulation of Polymer Latex

An aqueous latex comprising a quantity of anacrylonitrile-butadiene-styrene (ABS) graft copolymer was subjected to aseries of coagulation experiments. The ABS latex was obtained from anemulsion polymerisation process. The latex comprised 40.0 wt % solidmatter, the solid matter consisting of 97.7 wt % ABS, and 2.3 wt %tallow fatty acid potassium salt, with regard to the total weight of thesolid matter. The ABS comprised 32.1 wt % of polybutadiene, 45.6 wt % ofmoieties derived from styrene, and 22.3 wt % of moieties derived fromacrylonitrile, with regard to the total weight of the ABS copolymer. Theaverage particle size of the ABS copolymer in the latex was in the rangeof 0.05-0.50 μm.

In each of Experiments 1-4, a quantity of 42 liters (l) of the latex wasadded gradually over a period of 30 minutes (min) to a batch coagulatorvessel containing 50 l of water under stirring, where the vessel wassubjected to heating such that after 6 min the temperature reached 79°C., after 12 min the temperature reached 82° C., and after 30 min, sowhen addition of the latex was completed, the temperature reached 85° C.The temperature was further increased to 90° C. At that point a quantityof coagulant was added as per Table I below:

TABLE I Coagulant formulations Experiment 1(C) 2 3 4 Coagulant H₂SO₄CaCl₂ CaCl₂ CaCl₂ Quantity of coagulant 1.5 1.0 2.0 3.0

The H₂SO₄ used in the Experiment 1 was 98% H₂SO₄. The quantity ofcoagulant is presented as parts by weight per 100 parts by weight ofsolid matter in the latex.

The mixture was maintained at 90° C. for 10 minutes under stirring,after which a quantity of 150 l water was added to the vessel to cooldown the contents of the vessel to below 38° C.

Then, the coagulator vessel contents were transferred to a centrifugeand centrifuged to remove the water so that a wet cake having a moisturecontent of circa (ca.) 50 wt % was obtained. The wet cake was collectedand fed back to the empty coagulator vessel together with 75 l of waterof 50° C. After 10 minutes, another 125 l of water were added of suchtemperature to cool the contents of the vessel to below contents of thevessel to below 38° C. The coagulator vessel contents were transferredto the centrifuge and centrifuged for 10 minutes to obtain a wet cakehaving a moisture content of ca. 35 wt %. The obtained wet cake wassubjected to air drying at a temperature of 71° C. until it contained≤0.2 wt % of moisture. ABS Samples 1 through 4 were so obtained.

The obtained ABS samples were melt compounded with additives in a 7-zone30 mm twin-screw melt extruder according to the formulations in TableII:

TABLE II Compounding formulations Sample 1(C) 2 3 4 ABS 100.0 100.0100.0 100.0 MgO 0.25 — — — EBS wax 0.50 0.50 0.50 0.50 PEE 0.50 0.500.50 0.50 Phosphite 0.50 0.50 0.50 0.50

Wherein:

-   -   MgO is magnesium oxide, to neutralize the sulphuric acid, CAS        reg. nr. 1309-48-4;    -   EBS wax is ethylene-bis-stearamide wax, CAS reg. nr. 110-30-5;    -   PEE is polyoxyethylene ether having Mw or 8800, CAS reg. nr.        9003-11-6; and    -   Phosphite is Ultranox 626, bis(2,4-di-tert-butylphenyl)        pentaerythritol diphosphite, CAS reg. nr. 4122-20-3.

The melt extruder was operated at a speed of 250 revolutions per minute(rpm). The temperature settings of the melt extruder for each of thefour exemplary grades are indicated in Table III:

TABLE III Compounding extruder settings Zone 1 2 3 4 5 6 7 Temperature(° C.) 180 200 210 220 220 230 230

The product obtained from the compounding extruder was solidified andcut to pellets. From the pellets of each of Samples 1-4, films wereproduced using a 2.5 centimeter (cm) Sterling sheet extruder operatedunder the conditions as set out in Table IV:

TABLE IV Film extruder settings Zone 1 2 3 4 Die Temperature (° C.) 227238 154 249 249 Screw speed 20 rpm   Pressure 203 kPa Roll speed 2.3m/min Roll temp 82° C. 

For each of Samples 1-4, films were obtained of 11.4 cm width, 75 μmthickness, and 53 meter (m) length.

Determination of Film Properties

The films produced from the copolymer Samples 1-4 were tested to detectthe quantity of gels. In this context, gels are to be understood asareas of undispersed materials protruding from the surface of the filmfor more than 20 μm. The determination of the gel content was performedusing a sheet profilometer equipped with five 1.27 cm wide linearvariable displacement transducer sensors. The sample films were conveyedalong the sensors at a constant speed of 2.44 centimeter per second(cm/s). The gels were recorded as peaks recorded by the displacementsensors. For each sample, the quantity of peaks, and thus the quantityof gels, was counted for a 10-minute test run, equalling a length of14.6 m of film length.

Further, the quantity of residual calcium in the films were determinedin accordance with ASTM D7876 (2013). The results are in Table V.

TABLE V Sample 1(C) 2 3 4 Gel count 379 180 92 78 Residual Ca 0 14301440 1560

The objective to reduce gels is achieved by each of the Samples 2-4, inwhich the coagulant was a multivalent metal salt, over sample 1, whereinthe coagulant was an acid that was subsequently neutralized during thecompounding with a metal oxide MgO. Films of Samples 2 and 3 demonstratea particular desirable balance of low gel count at low metal saltquantities added, which is desirable since this positively impactsprocess economics as well as residual metal content in the copolymermaterial. The presence of a low residual metal content is desirable as atoo high content is understood to attribute to the occurrence of surfacedefects.

Set forth below are some aspects of the copolymer disclosed herein.

Aspect 1: A core-shell graft copolymer , preferably a core-shellacrylonitrile-butadiene-styrene graft copolymer, produced by coagulationof an aqueous latex comprising ≥10.0 wt % and <40 wt % of particles ofthe copolymer and a quantity of a surfactant, wherein the coagulationinvolves the addition of a quantity of a lithium salt or a multivalentmetal salt, preferably a bivalent or trivalent metal salt.

Aspect 2: The core-shell graft copolymer according to Aspect 1, whereinthe core-shell graft copolymer is an acrylonitrile-butadiene-styrenegraft copolymer, a methyl methacrylate-butadiene-styrene graftcopolymer, or an acrylonitrile-styrene-acrylate rubber graft copolymer;preferably the core-shell graft copolymer is anacrylonitrile-butadiene-styrene graft copolymer.

Aspect 3: The core-shell graft copolymer according to any one of Aspects1-2, wherein the surfactant is a fatty acid or a salt thereof, or amixture of fatty acids or salts thereof.

Aspect 4: The core-shell graft copolymer according to any one of Aspects1-3, wherein the metal is selected from beryllium, magnesium, calcium,strontium, barium, radium, aluminium and zinc, and is preferablymagnesium, aluminium, zinc or calcium.

Aspect 5: The core-shell graft copolymer according to any one of Aspects1-4, wherein the salt is a halogenide, preferably a chloride, asulphate, a biphosphate, a hydrogen phosphate, a bisulphate, abisulphite, a bicarbonate, a chlorate, or a nitrate.

Aspect 6: The core-shell graft copolymer according to any one of Aspects1-5, wherein the multivalent metal salt or lithium salt is selected frommagnesium sulphate, magnesium chloride, magnesium nitrate, calciumchloride, calcium nitrate, aluminium chloride, aluminium nitrate, zincchloride, zinc sulphate, zinc nitrate, lithium chloride, lithiumnitrate, or lithium sulphate; preferably the coagulation involves atleast one of lithium chloride, lithium nitrate, or lithium sulphate.

Aspect 7: The core-shell graft copolymer according to any one of Aspects1-6, wherein the multivalent metal salt is a salt of an alkaline earthmetal.

Aspect 8: The core-shell graft copolymer according any one of Aspects1-7, wherein the multivalent metal salt is added to the latex forcoagulation in a quantity of 0.5-2.5 wt % with regard to the weight ofthe core-shell graft copolymer particles present in the latex.

Aspect 9: The core-shell graft copolymer according any one of Aspects1-8, wherein the coagulation of the aqueous latex is free of magnesiumoxide.

Aspect 10: The core-shell graft copolymer according any one of Aspect1-9, wherein the copolymer comprises elastomeric core particles, whereinthe elastomeric core particles are trimodal, preferably, wherein theelastomeric core particles have a first peak at <200 nm, a second peakat 200-500 nm, and a third peak at >800 nm.

Aspect 11: A process for the production of a core-shell graft copolymercomprising coagulation of an aqueous latex comprising a quantity ofparticles of the copolymer and a quantity of a fatty acid surfactant,wherein the coagulation involves the addition of 0.5-2.5 wt % of amultivalent metal salt with regard to the weight of the core-shellcopolymer particles present in the latex.

Aspect 12: The process according to Aspect 11, wherein: the metalcomprises at least one selected from beryllium, magnesium, calcium,strontium, barium, radium, aluminium, or zinc.

Aspect 13: The process according to any one of Aspect 11-12, wherein:the metal comprises at least one selected from magnesium, aluminium,zinc, or calcium.

Aspect 14: The process according to Aspect 11-13, wherein: the saltcomprises at least one of a halogenide, a sulphate, a biphosphate, ahydrogen phosphate, a bisulphate, a bisulphite, a bicarbonate, achlorate, or a nitrate; preferably the salt comprises a halogenide; morepreferably the salt comprises chloride.

Aspect 15: The process according to any one of Aspects 11-14, whereinthe multivalent metal salt comprises at least one (preferably one)selected from magnesium sulphate, magnesium chloride, magnesium nitrate,calcium chloride, calcium nitrate, aluminium chloride, aluminiumnitrate, zinc chloride, zinc sulphate, or zinc nitrate; preferablywherein the multivalent metal salt comprises calcium chloride.

Aspect 16: The process according to any one of Aspects 11-15, whereinthe core-shell graft copolymer comprises at least one (preferably one)selected from an acrylonitrile-butadiene-styrene graft copolymer, amethyl methacrylate-butadiene-styrene graft copolymer, anacrylonitrile-styrene-acrylate rubber graft copolymer, or anacrylonitrile-styrene-silicone rubber graft copolymer.

Aspect 17: An article comprising a surface area comprising a core-shellgraft copolymer according to any one of Aspects 1-10 or of a core-shellgraft copolymer obtained by the process of any one of Aspects 11-16.

Aspect 18: The article according to Aspect 17, wherein the surface areacomprising the core-shell graft copolymer is coated with a metalliccoating; preferably the whole surface area is coated with the metalliccoating.

Aspect 19: The article according to Aspect 18, wherein the metalliccoating is applied to the article by means of electroplating.

Aspect 20: The article according to any one of Aspects 17-19, whereinthe metallic coating comprises at least one selected from copper,nickel, gold, silver, platinum, or alloys thereof.

The terms “a” and “an” and “the” do not denote a limitation of quantity,and are to be construed to cover both the singular and the plural,unless otherwise indicated herein or clearly contradicted by context.“Or” means “and/or” unless clearly indicated otherwise by context.Unless defined otherwise, technical and scientific terms used hereinhave the same meaning as is commonly understood by one of skill in theart to which this invention belongs. A “combination” is inclusive ofblends, mixtures, alloys, reaction products, and the like. “One or moreof the foregoing” means at least one of the listed material. All amountstotal 100 wt %. All ranges disclosed herein are inclusive of theendpoints, and the endpoints are independently combinable with eachother. In general, the disclosure may alternately comprise, consist of,or consist essentially of, any appropriate components herein disclosed.The disclosure may additionally, or alternatively, be formulated so asto be devoid, or substantially free, of any components, materials,ingredients, adjuvants or species used in the prior art compositions orthat are otherwise not necessary to the achievement of the functionand/or objectives of the present disclosure.

Unless specified to the contrary herein, all test standards are the mostrecent standard in effect as of the filing date of this application, or,if priority is claimed, the filing date of the earliest priorityapplication in which the test standard appears. All cited patents,patent applications (including any priority application), and otherreferences are incorporated herein by reference in their entirety.However, if a term in the present application contradicts or conflictswith a term in the incorporated reference, the tet in from the presentapplication takes precedence over the conflicting term from theincorporated reference.

1. A core-shell graft copolymer, preferably a core-shell acrylonitrile-butadiene-styrene graft copolymer, produced by coagulation of an aqueous latex comprising ≥10.0 wt % and <40 wt % of particles of the copolymer and a quantity of a surfactant, wherein the coagulation involves the addition of a quantity of a lithium salt or a multivalent metal salt, preferably a bivalent or trivalent metal salt.
 2. The core-shell graft copolymer according to claim 1, wherein the core-shell graft copolymer is an acrylonitrile-butadiene-styrene graft copolymer, a methyl methacrylate-butadiene-styrene graft copolymer, or an acrylonitrile-styrene-acrylate rubber graft copolymer.
 3. The core-shell graft copolymer according to claim 1, wherein the core-shell graft copolymer is an acrylonitrile-butadiene-styrene graft copolymer.
 4. The core-shell graft copolymer according to claim 1, wherein the surfactant is a fatty acid or a salt thereof, or a mixture of fatty acids or salts thereof.
 5. The core-shell graft copolymer according to claim 1, wherein the metal comprises at least one selected from beryllium, magnesium, calcium, strontium, barium, radium, aluminium, or zinc; preferably at least one selected from magnesium, aluminium, zinc, or calcium.
 6. The core-shell graft copolymer according to claim 1, wherein the salt is a halogenide (preferably a chloride), a sulphate, a biphosphate, a hydrogen phosphate, a bisulphate, a bisulphite, a bicarbonate, a chlorate, or a nitrate.
 7. The core-shell graft copolymer according to claim 1, wherein the multivalent metal salt or lithium salt is selected from at least one of magnesium sulphate, magnesium chloride, magnesium nitrate, calcium chloride, calcium nitrate, aluminium chloride, aluminium nitrate, zinc chloride, zinc sulphate, zinc nitrate, lithium chloride, lithium nitrate, or lithium sulphate.
 8. The core-shell graft copolymer according to claim 1, wherein the multivalent metal salt is a salt of an alkaline earth metal.
 9. The core-shell graft copolymer according claim 1, wherein the multivalent metal salt is added to the latex for coagulation in a quantity of 0.5-2.5 wt % with regard to the weight of the core-shell graft copolymer particles present in the latex.
 10. The core-shell graft copolymer according to claim 1, wherein the coagulation of the aqueous latex is free of magnesium oxide.
 11. The core-shell graft copolymer according to claim 1, wherein the copolymer comprises elastomeric core particles, wherein the elastomeric core particles are trimodal, preferably, wherein the elastomeric core particles have a first peak at <200 nm, a second peak at 200-500 nm, and a third peak at >800 nm.
 12. A process for the production of a core-shell graft copolymer comprising coagulation of an aqueous latex comprising a quantity of particles of the copolymer and a quantity of a fatty acid surfactant, wherein the coagulation involves the addition of 0.5-2.5 wt % of a multivalent metal salt with regard to the weight of the core-shell copolymer particles present in the latex.
 13. The process according to claim 12, wherein: the metal comprises at least one selected from beryllium, magnesium, calcium, strontium, barium, radium, aluminium, or zinc; preferably comprises at least one of magnesium, aluminium, zinc, or calcium; and/or the salt comprises at least one of a halogenide (preferably a chloride), a sulphate, a biphosphate, a hydrogen phosphate, a bisulphate, a bisulphite, a bicarbonate, a chlorate, or a nitrate.
 14. The process according to claim 12, wherein the core-shell graft copolymer comprises at least one, preferably comprises one, selected from an acrylonitrile-butadiene-styrene graft copolymer, a methyl methacrylate-butadiene-styrene graft copolymer, an acrylonitrile-styrene-acrylate rubber graft copolymer, and an acrylonitrile-styrene-silicone rubber graft copolymer, and wherein the multivalent metal salt comprises at least one, preferably one, selected from magnesium sulphate, magnesium chloride, magnesium nitrate, calcium chloride, calcium nitrate, aluminium chloride, aluminium nitrate, zinc chloride, zinc sulphate, and zinc nitrate.
 15. An article comprising a surface area comprising a core-shell graft copolymer according to claim
 1. 16. The article according to claim 15, wherein the surface area comprising the core-shell graft copolymer is coated with a metallic coating.
 17. The article according to claim 6, wherein the metallic coating is applied to the article by means of electroplating.
 18. The article according to claim 15, wherein the metallic coating comprises at least one selected from copper, nickel, gold, silver, platinum, or alloys thereof.
 19. An article comprising a surface area comprising a core-shell graft copolymer obtained by the process of claim
 12. 20. The process according to claim 13, wherein the core-shell graft copolymer comprises at least one, preferably comprises one, selected from an acrylonitrile-butadiene-styrene graft copolymer, a methyl methacrylate-butadiene-styrene graft copolymer, an acrylonitrile-styrene-acrylate rubber graft copolymer, and an acrylonitrile-styrene-silicone rubber graft copolymer, and wherein the multivalent metal salt comprises at least one, preferably one, selected from magnesium sulphate, magnesium chloride, magnesium nitrate, calcium chloride, calcium nitrate, aluminium chloride, aluminium nitrate, zinc chloride, zinc sulphate, and zinc nitrate. 